الفهرس 
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Abstract
Water is a vital resource for life on Earth; covering 71% of its surface. Sea and ocean water account for the largest proportion of water on Earth, at about 96.5%. Fresh water accounts for only about 2.5% of the water on earth. Thus, the availability of potable water is diminishing day by day,; whereas the demand for potable water is fast growing. Thus, this problem must be overcome by removing salts from saline water by desalinating salinity water .
Desalination is one among the only closest and greatest solutions to the scarcity. of water. And because fossil fuels are scarce and expensive, it was necessary to use energy from sun as a renewable energy source in water desalination process. The basin-type solar still is the most common and easiest to design. However, its thermal efficiency is low and so some ways should be followed to enhance its productivity. The present thesis aims at studying a method for enhancing the performance of solar desalination units by using three dyes of different photo-stability values which are added to water basin of stills to increase the absorptivity of water for the solar irradiation; thus raising its temperature and hence raising its productivity. Hourly productivity, total productivity, efficiency and its production behavior along the day are measured and compared. Besides, the effect of water depth on still effectiveness is examined and the results are presented in the thesis. The dyes used are: Black Naphthylamine 10 BR (referred to as Black Dye), Dark Green Dye (referred to as Green Dye) and Red Carmoisine BA Ex (referred to as Red Dye). Results showed that the best dye in performance is the Black dye. A dye solution of 200 ppm concentration gave the highest productivity. For all stills, daily still productivity decreases with growing of brine depth in the basin. The percentage increase in total still productivity due to the use of dyes was 37.55, 29.02 and 20.48%, for the Black, Green and Red dyes solutions, respectively; compared to the reference still. Percentage reduction of still productivity due to increasing water depth was 12.77, 8.95 and 9.17% for the Black, Green and Red dye solutions; when increasing water depth from 2 to 3 cm. The corresponding values were 16.86, 14.01 and 15.08% when increasing water depth from 3 to 4 cm, for the same sequence of dyes.
The thesis consists of 5 basic chapters as follows:
Chapter one: Is an introduction for the work performed in the study
Chapter two: Is a literature survey for the previous studies made in the same subject in the last 2 decades.
Chapter three: Gives a theoretical background for the topics handled in the study.
Chapter four: Is the experimental part showing the experimental setup, the materials used, the procedure and the instrumentations used.
Chapter five: Presents the results obtained from the experimental work, its analysis and discussion.
Beside these five main chapters, the thesis includes the conclusions obtained from the work, a list of the references used in the study and the thesis ends with an Arabic summary.
At the beginning of the thesis these is a list of figures, list of tables and abbreviations used in the thesis.